Preprints with The Lancet is part of SSRN´s First Look, a place where journals identify content of interest prior to publication. Authors have opted in at submission to The Lancet family of journals to post their preprints on Preprints with The Lancet. The usual SSRN checks and a Lancet-specific check for appropriateness and transparency have been applied. Preprints available here are not Lancet publications or necessarily under review with a Lancet journal. These preprints are early stage research papers that have not been peer-reviewed. The findings should not be used for clinical or public health decision making and should not be presented to a lay audience without highlighting that they are preliminary and have not been peer-reviewed. For more information on this collaboration, see the comments published in The Lancet about the trial period, and our decision to make this a permanent offering, or visit The Lancet´s FAQ page, and for any feedback please contact email@example.com.
Effect of Distributing Locally Produced Cloth Facemasks on COVID-19-Like Illness and All-Cause Mortality – a Cluster-Randomised Controlled Trial in Urban Guinea-Bissau
20 Pages Posted: 5 Jan 2023More...
Background: Facemasks have been employed to mitigate the spread of SARS-CoV-2. The community effect of providing cloth facemasks on COVID-19 morbidity and mortality is unknown.
Methods: In a cluster randomised trial in urban Bissau, Guinea-Bissau, between 20 July 2020 and 22 January 2021 trial participants (aged 10+ years) living in intervention clusters received two 2-layer cloth facemasks. All participants received information on COVID-19 prevention. Trial participants were followed through a telephone interview for COVID-19-like illness (3+ symptoms), care seeking, and mortality for 4 months. End-of-study home visits ensured full mortality information and distribution of facemasks to the control group. Proportions experiencing outcomes were compared in logistic regression models with generalised estimating equation-based correction for cluster. Facemasks use was mandated. Facemask use in public areas was assessed by direct observation.
Findings: Among the 39,574 trial participants enrolled, 95% reported exposure to groups of >20 persons and 99% reported facemasks use, with no difference between trial arms. Observed use was substantially lower (~40%) with a 3% (0-6%) absolute difference between control and intervention clusters. Half of those wearing a facemask wore it correctly. Few participants reported COVID-19-like illness (<2%); proportions did not differ by trial arm: Odds Ratio (OR)=0.81 (95%CI:0.57-1.15). 177 participants reported consultations and COVID-19-like illness (OR=0.83 (0.56-1.24)); 89 persons died (OR=1.34 (0.89-2.02)).
Interpretation: Trial participants were exposed to many people, but facemasks were mostly not worn or not worn correctly. Providing facemasks and messages about correct use did not substantially increase use and had limited impact on morbidity and mortality.
Funding Statement: Novo Nordisk Foundation (NNF20SH0064649), Reinholdt W. Jorck Fonden (20-JP-0299), Augustinus fonden (20-1196), COWIfonden (APE/knl/A_149.14) and University of Southern Denmark.
Declaration of Interests: None to declare.
Ethics Approval Statement: Our trial protocol was approved by the Guinean National Ethics Committee (Comité Nacional de Ética na Saúde, reference: 79/CNES/INASA/2020).
Trial Registration: clinicaltrials.gov: NCT04471766
Keywords: COVID-19, facemasks, mortality, morbidity, Public Health, communicable disease control
Suggested Citation: Suggested Citation